Hi guys,
I am using the LMX2492 evaluation board in my project to synthesize a sawtooth ramp that needs to ramp from 2.35 GHz to 2.45 GHz (RF/4 channel). I have managed to generate a continuous frequency output as well as a ramp function, so I know that the PLL is locking, however, i encountered a few issues:
1) When I generate the ramp I am getting unexpected frequency components starting at 2.32 GHz. Since I can't view the frequency vs time plot to see the actual sawtooth function I am not exactly sure how to explain this. I read through the data sheet and set up the device manually using the "register" tab (checking the settings in the bits tab) in codeloader, as the "ramp calculator" tab always crashed and failed to setup the device properly. As I saw in this post:
there is an issue with readback, which I also encountered, hence, it is difficult to troubleshoot the issue with the ramp. I also attached the image of the bits/pins tab that I used to set up my 100 Mhz, 100 us ramp. Any insight into how I can get a better ramp will be appreciated.
2)Furthermore, I encountered issues when trying to set the bandwidth to 700 MHz (RF channel 9.4 to 10.1 GHz), which converts to 175 MHz at the RF/4 channel, the maximum bandwidth that I was able to achieve was 400 MHz at RF channel, is there anything I can do to attain the 700 MHz bandwidth?
3)Finally, is there a minimum ramp length that one can setup? As when I made the 100 MHz ramp with the duration of 3 us, I once again ran into problems. The ramp looked better on the spectrum analyzer (i.e no unwanted frequency components below 2.35 GHz) but the power level has dropped drastically. This can be seen below, with the configuration image following the spectrum analyzer plot.
Any information that can help with those issues will be appreciated, thank you
Regards,
Ivan
